Touches issue #36: Add SDTM examples (VS, DM, AE)

[ShiyuC]

Pull Request

Add examples to describe how to create VS, DM, AE domain using raw datasets from {pharmaverseraw} package using {sdtm.oak} package

Before you submit your pull request, take a look at the following checklist. Many thanks for your contribution!

• Title: Place Closes #36 at the beginning of your PR title. Use the Edit button in the top-right if you need to update.
• Linked Issue: Ensure the related issue is linked in the "Development Section" on the right-hand side.
• First Contribution: If this is your first contribution, add yourself to the DESCRIPTION file.
• Impact on Examples: If your updates impact any examples, review locally for warnings or errors in the impacted example pages.
• Merge Conflicts: Developers should address any merge conflicts and merge upon successful review.
• New Packages: If new packages were used, ensure they are included in the DESCRIPTION file's Imports section.
• Updated Examples: If you added or updated an example, ensure it runs on the latest CRAN release versions of all packages used.
• Testing Instructions: Nothing specific. Just run the code :)

[ShiyuC]

@rammprasad I have added articles for VS, DM and AE. Please conduct a review when you get a chance.

[rammprasad]

Looks great, TY, Shiyu.

[rammprasad]

@bms63 @rossfarrugia - Can we review and merge this to main before the Posti conf? (Tuesday). If there are any outstansing issues, we can address it in the next PR.

[rossfarrugia]

I made some minor updates for presentability to make consistent with the other articles, and I re-ordered to match the ADaM order. For the actual examples I trust the authors here as the subject matter experts. I'll approve and merge this now and any further tweaks can be made with new issues/PRs